iPhone directs incoming calls to voice mail without ringing when I am on the phone

microKOAT wrote:

Correct - I am already on the phone and the phone does not ring. When I am not on the phone, it rings as normal.

So, did you contact your carrier to make sure that call waiting was enabled on your account?

It sounds as if you don't have call waiting enabled on your line. Contact your carrier.

• you must ensure your iPhone is connected to a stable cellular network.
• Also, try turning on and off Airplane mode.
• If you have set up any Focus or DND mode, turn that off.
• Disable Silence Unknown Callers by going to Settings → Phone. Tap Silence Unknown Callers → Toggle off Silence Unknown Callers.

I hope this helps!!

ava_biswas_official wrote:

• you must ensure your iPhone is connected to a stable cellular network.

They are already on a call - that implies a stable cellular network

• Also, try turning on and off Airplane mode.

That is a non-starter - turning on and off Airplane mode would disconnect the call they are on.

• If you have set up any Focus or DND mode, turn that off.

The phone is already unlocked, so DND is irrelevant

Disable Silence Unknown Callers by going to Settings → Phone. Tap Silence Unknown Callers → Toggle off Silence Unknown Callers• .

As explained, this is a number that works when they are not on a call, so it clearly it is not being blocked by Silence Unknown Callers.

I hope this helps!!

Well, it actually is no help at all. It would be prudent to read and understand a question before suggesting a solution.

ava_biswas_official wrote:

• you must ensure your iPhone is connected to a stable cellular network.

If they are already on a call, I would imagine they are properly connected to the network.

microKOAT wrote:

As a matter of fact, we just found that setting on the phone and switched it so that was the problem.

Excellent!